U.S. patent number 8,768,227 [Application Number 13/770,796] was granted by the patent office on 2014-07-01 for developing member including elastic member containing cured product of addition-curing silicone rubber mixture, processing cartridge including the developing member, and electrophotographic apparatus including the developing member.
This patent grant is currently assigned to Canon Kabushiki Kaisha. The grantee listed for this patent is Canon Kabushiki Kaisha. Invention is credited to Kunimasa Kawamura, Takashi Kusaba, Minoru Nakamura, Shohei Urushihara, Masaki Yamada.
United States Patent |
8,768,227 |
Urushihara , et al. |
July 1, 2014 |
Developing member including elastic member containing cured product
of addition-curing silicone rubber mixture, processing cartridge
including the developing member, and electrophotographic apparatus
including the developing member
Abstract
A developing roller includes: a mandrel; an elastic layer
provided for an outer periphery of the mandrel, the elastic layer
including an addition-curing silicone rubber; and a surface layer
provided for an outer periphery of the elastic layer, in which: the
elastic layer includes a compound represented by the following
formula (1); when the content of such a compound that n in the
formula (1) represents an integer of 3 to 12 in the elastic layer
is represented by P1, and the content of such a compound that n in
the formula (1) represents an integer of 13 to 20 in the elastic
layer is represented by P2, P1+P2 is 5,000 ppm by mass to 12,000
ppm by mass; and P1 is 1,500 ppm by mass to 6,000 ppm by mass (In
the formula (1), n represents an integer of 3 to 20):
##STR00001##
Inventors: |
Urushihara; Shohei (Suntou-gun,
JP), Nakamura; Minoru (Mishima, JP),
Kawamura; Kunimasa (Mishima, JP), Yamada; Masaki
(Mishima, JP), Kusaba; Takashi (Suntou-gun,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Canon Kabushiki Kaisha |
Tokyo |
N/A |
JP |
|
|
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
50233413 |
Appl.
No.: |
13/770,796 |
Filed: |
February 19, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20140072350 A1 |
Mar 13, 2014 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
PCT/JP2012/006120 |
Sep 26, 2012 |
|
|
|
|
Foreign Application Priority Data
|
|
|
|
|
Sep 7, 2012 [JP] |
|
|
2012-196992 |
|
Current U.S.
Class: |
399/286 |
Current CPC
Class: |
G03G
21/1814 (20130101); G03G 15/0808 (20130101); G03G
15/0818 (20130101) |
Current International
Class: |
G03G
15/08 (20060101) |
Field of
Search: |
;399/279,286 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
4-76577 |
|
Mar 1992 |
|
JP |
|
11-167246 |
|
Jun 1999 |
|
JP |
|
11-223987 |
|
Aug 1999 |
|
JP |
|
2000-265150 |
|
Sep 2000 |
|
JP |
|
2000-313807 |
|
Nov 2000 |
|
JP |
|
2001-83797 |
|
Mar 2001 |
|
JP |
|
2003-128920 |
|
May 2003 |
|
JP |
|
2008-74913 |
|
Apr 2008 |
|
JP |
|
2008-163282 |
|
Jul 2008 |
|
JP |
|
03/035762 |
|
May 2003 |
|
WO |
|
Primary Examiner: Royer; William J
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper and
Scinto
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of International Application No.
PCT/JP2012/006120, filed Sep. 26, 2012, which claims the benefit of
Japanese Patent Application No. 2012-196992, filed Sep. 7, 2012.
Claims
What is claimed is:
1. A developing member, comprising: a substrate; an elastic layer
provided on the substrate, the elastic layer comprising a cured
product of an addition-curing silicone rubber mixture; and a
surface layer provided on the elastic layer, wherein: the elastic
layer comprises a compound represented by the following formula
(1): ##STR00004## in the formula (1), n represents an integer of 3
or more and 20 or less, and wherein: when a content of the compound
in which n represents an integer of 3 or more and 12 or less in the
elastic layer is represented by P1 ppm by mass, and a content of
the compound in which n represents an integer of 13 or more and 20
or less in the elastic layer is represented by P2 ppm by mass,
P1+P2 is 5,000 ppm by mass or more and 12,000 ppm by mass or less;
and P1 is 1,500 ppm by mass or more and 6,000 ppm by mass or
less.
2. The developing member according to claim 1, wherein the P1+P2 is
6,000 ppm by mass or more and 11,000 ppm by mass or less.
3. The developing member according to claim 2, wherein the P1+P2 is
7,000 ppm by mass or more and 10,000 ppm by mass or less.
4. The developing member according to claim 1, wherein the P1 is
2,000 ppm by mass or more and 5,500 ppm by mass or less.
5. The developing member according to claim 4, wherein the P1 is
2,500 ppm by mass or more and 5,000 ppm by mass or less.
6. The developing member according to claim 1, wherein the
addition-curing silicone rubber mixture comprises the following
component (A), component (B), and component (C): (A) an
organopolysiloxane having, in a molecule thereof, at least two
alkenyl groups bonded to a silicon atom; (B) an organopolysiloxane
having, in a molecule thereof, at least three hydrogen atoms bonded
to a silicon atom; and (C) a platinum-based catalyst.
7. The developing member according to claim 6, wherein the
component (A) has a weight-average molecular weight of 20,000 or
more and 200,000 or less.
8. The developing member according to claim 1, wherein the elastic
layer comprises an inorganic filler at a ratio of 0.1 mass % or
more and 24 mass % or less.
9. A process cartridge, comprising: a toner; a toner container
storing the toner; and a developing member for carrying the toner
in the toner container on a surface thereof and conveying the toner
to a developing region, the process cartridge being constituted to
be attachable to and detachable from a main body of an
electrophotographic apparatus, wherein the developing member
comprises the developing member according to claim 1.
10. An electrophotographic apparatus, comprising: a toner; a toner
container storing the toner; and a developing member for carrying
the toner in the toner container on a surface thereof and conveying
the toner to a developing region, wherein the developing member
comprises the developing member according to claim 1.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a developing member to be
incorporated into an electrophotographic apparatus, and a process
cartridge and an electrophotographic apparatus each using the
developing member.
2. Description of the Related Art
A developing member to be used in an electrophotographic apparatus
may be used in various temperature environments. Accordingly, a
developing member having low temperature dependence has been
required. A temperature variation may cause, for example, a change
in shape of a developing member due to its thermal expansion. A
silicone rubber is suitably used in an elastic layer of a
developing member. However, the silicone rubber is more liable to
expand thermally than any other rubber is.
It can be said that a variation in size of the elastic layer of a
developing member due to its surrounding temperature or humidity is
a problem to be solved in order that electrophotographic images
having stable quality may be provided. To solve such problem,
Patent Literature 1 proposes a silicone rubber composition that
provides a silicone rubber having a low expansion coefficient
through the addition of an abundance of a silica-based filler
having a small surface area. In addition, Patent Literature 2
proposes a silicone rubber composition that provides a silicone
rubber having a low viscosity and a low expansion coefficient
through the addition of a large amount of silica whose isolated
silanol group content has been specified.
CITATION LIST
Patent Literature
PTL 1: Japanese Patent Application Laid-Open No. 2000-265150 PTL 2:
Japanese Patent Application Laid-Open No. 2003-128920
SUMMARY OF THE INVENTION
An investigation conducted by the inventors of the present
invention has shown that the construction according to any one of
Patent Literatures 1 and 2 is expected to exert a suppressing
effect on the thermal expansion of a silicone rubber. However, the
application of the technology according to any one of Patent
Literatures 1 and 2 to a developing member may reduce the
elasticity of its elastic layer. As a result, when a member such as
a toner control blade abuts on the surface of the developing member
over a long time period, a plastic deformation that is not easily
recovered (hereinafter, sometimes referred to as "C-set") may occur
at the abutting portion in the surface of the developing member. A
portion in the developing member where the C-set has occurred is
different from any other portion in, for example, toner
conveyability. Accordingly, when an electrophotographic image is
formed with such developing member, density nonuniformity derived
from the C-set may appear in the electrophotographic image.
In view of the foregoing, the present invention is directed to
providing a developing member that has reduced the thermal
expansion of its elastic layer and hardly causes a plastic
deformation even after abutting with an abutting member for a long
time period. Further, the present invention is directed to
providing a process cartridge and an electrophotographic apparatus
conducive to the formation of a high-quality electrophotographic
image.
According to one aspect of the present invention, there is provided
a developing member, comprising:
a substrate;
an elastic layer provided on the substrate, the elastic layer
comprising a cured product of an addition-curing silicone rubber
mixture; and
a surface layer provided on the elastic layer,
wherein:
the elastic layer comprises a compound represented by the following
formula (1):
##STR00002##
in the formula (1), n represents an integer of 3 or more and 20 or
less, and wherein:
when
a content of the compound in which n represents an integer of 3 or
more and 12 or less in the elastic layer is represented by P1 ppm
by mass, and
a content of the compound in which n represents an integer of 13 or
more and 20 or less in the elastic layer is represented by P2 ppm
by mass,
P1+P2 is 5,000 ppm by mass or more and 12,000 ppm by mass or less;
and
P1 is 1,500 ppm by mass or more and 6,000 ppm by mass or less.
According to another aspect of the present invention, there is
provided a process cartridge, including: a toner; a toner container
storing the toner; and a developing member for carrying the toner
in the toner container on a surface thereof and conveying the toner
to a developing region, the process cartridge being constituted to
be attachable to and detachable from a main body of an
electrophotographic apparatus, in which the developing member
includes the above-mentioned developing member.
According to the present invention, also provided is an
electrophotographic apparatus, including: a toner; a toner
container storing the toner; and a developing member for carrying
the toner in the toner container on a surface thereof and conveying
the toner to a developing region, in which the developing member
includes the above-mentioned developing member.
According to the present invention, it is possible to provide the
developing member that has reduced the thermal expansion of its
elastic layer and hardly causes a plastic deformation at an
abutting portion even after abutting with an abutting member for a
long time period. According to the present invention, it is also
possible to provide the process cartridge and the
electrophotographic apparatus conducive to the formation of a
high-quality electrophotographic image.
Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference
to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of an example of a developing roller
according to the present invention.
FIG. 2 is a sectional view of an example of a process cartridge
according to the present invention.
FIG. 3 is a sectional view of an example of an electrophotographic
apparatus according to the present invention.
FIG. 4 is a schematic view of a device for measuring the shape of
the developing roller according to the present invention.
DESCRIPTION OF THE EMBODIMENTS
Preferred embodiments of the present invention will now be
described in detail in accordance with the accompanying
drawings.
(Developing Member)
A developing member according to the present invention includes a
substrate, an elastic layer, and a surface layer. FIG. 1
illustrates a sectional view in a direction perpendicular to the
axis of a roller-shaped developing member, i.e., developing roller
according to the present invention. A developing roller 1
illustrated in FIG. 1 is such that an elastic layer 3 is provided
for the outer periphery of a mandrel substrate 2 and a surface
layer 4 is provided for the outer periphery of the elastic layer
3.
(Substrate)
The substrate functions as an electrode and supporting member for
the developing member. Accordingly, the substrate is constituted
of, for example, a conductive material such as: a metal or an alloy
such as aluminum, a copper alloy, or stainless steel; iron plated
with chromium or nickel; or a synthetic resin having conductivity.
A hollow or solid substrate can be used as the substrate in the
developing member.
(Elastic Layer)
The elastic layer 3 contains a cured product of an addition-curing
silicone rubber and contains a compound represented by the
following formula (1).
##STR00003## (In the formula (1), n represents an integer of 3 or
more and 20 or less.)
<P1, P2, P1+P2>
In the present invention, when the content of such a compound that
n in the formula (1) represents an integer of 3 or more and 12 or
less in the elastic layer is represented by P1 ppm by mass, and the
content of such a compound that n in the formula (1) represents an
integer of 13 or more and 20 or less in the elastic layer is
represented by P2 ppm by mass, P1+P2 is 5,000 ppm by mass or more
and 12,000 ppm by mass or less. Setting the P1+P2 to 5,000 ppm by
mass or more can effectively suppress the molecular mobility of the
silicone rubber and hence can effectively suppress the thermal
expansion of the elastic layer.
In addition, setting the P1+P2 to 12,000 ppm by mass or less can
sufficiently suppress a reduction in rubber elasticity due to the
entanglement of the silicone rubber as a main component and a
cyclic siloxane. Here, the P1+P2 is preferably 6,000 ppm by mass or
more and 11,000 ppm by mass or less, particularly preferably 7,000
ppm by mass or more and 10,000 ppm by mass or less, more preferably
8,000 ppm by mass or more and 9,000 ppm by mass or less.
In addition, the P1 is 1,500 ppm by mass or more and 6,000 ppm by
mass or less. Setting the P1 to 1,500 ppm by mass or more can
sufficiently suppress the occurrence of the plastic deformation,
i.e., C-set of the elastic layer. In addition, setting the P1 to
6,000 ppm by mass or less can effectively suppress a reduction in
rubber elasticity of the elastic layer due to, for example, the
bleeding of the cyclic siloxane toward the developing member. Here,
the P1 is set to preferably 2,000 ppm by mass or more and 5,500 ppm
by mass or less, particularly preferably 2,500 ppm by mass or more
and 5,000 ppm by mass or less, more preferably 3,000 ppm by mass or
more and 4,000 ppm by mass or less. It should be noted that the P1
and the P2 can be measured by a method to be described later.
The compound represented by the formula (1) is more rigid than a
high-molecular weight polysiloxane having a linear structure.
Accordingly, the elastic layer containing the cyclic siloxane
represented by the formula (1) at the above-mentioned ratio
suppresses a rise of the molecular mobility due to thermal energy
even under a high-temperature environment, and hence the thermal
expansion of the elastic layer can be suppressed.
In addition, the compound represented by the formula (1) has a
lower molecular weight than that of the silicone rubber.
Accordingly, a reduction in rubber elasticity due to its
entanglement with the silicone rubber hardly occurs. In particular,
such compound that n in the formula (1) represents 3 or more and 12
or less has a rigid molecular structure and the structure is hardly
changed even by an external pressure. Accordingly, for example,
even when a toner control blade or the like abuts on the developing
member over a long time period, the occurrence of a plastic
deformation that is not easily recovered in the elastic layer can
be effectively suppressed.
As described above, the thermal expansion of the elastic layer
according to the present invention is suppressed and its plastic
deformation hardly occurs. Accordingly, the occurrence of a
horizontal streak image resulting from the plastic deformation can
also be effectively suppressed.
(Addition-Curing Silicone Rubber Mixture)
The addition-curing silicone rubber mixture to be used as a raw
material for the elastic layer of the present invention may
contain, for example, the following component (A), component (B),
and component (C):
(A) an organopolysiloxane having, in a molecule thereof, at least
two alkenyl groups bonded to a silicon atom;
(B) an organopolysiloxane having, in a molecule thereof, at least
three hydrogen atoms bonded to a silicon atom; and
(C) a platinum-based catalyst.
The molecular structure of the component (A) may be any one of
linear and branched structures, and from the viewpoints of
satisfactory tensile strength, tear strength, and breaking strength
of the cured product, a linear structure is preferred. Examples of
the alkenyl group include a vinyl group, an allyl group, a propenyl
group, an isopropenyl group, a butenyl group, an isobutenyl group,
a pentenyl group, and a hexenyl group. Of those, a vinyl group is
preferred as the alkenyl group.
The organopolysiloxane as the component (A) has at least two
alkenyl groups, and these alkenyl groups may be identical to each
other or different from each other. Examples of the component (A)
include a both-terminal-vinyl-sealed polydimethylsiloxane and a
polydimethylsiloxane having a side-chain vinyl group. Only one kind
of those materials may be used alone, or two or more kinds thereof
may be used in combination. The weight-average molecular weight
(Mw) of the component (A) is preferably 20,000 or more and 200,000
or less, particularly more preferably 30,000 or more and 150,000 or
less.
Here, a weight-average molecular weight (Mw) is defined as a value
obtained by measurement involving employing gel permeation
chromatography. Specifically, a high-performance liquid
chromatograph analyzer (product name: HLC-8120GPC; manufactured by
TOSOH CORPORATION) in which two GPC columns (trade name: TSKgel
SuperHM-m; manufactured by TOSOH CORPORATION) are connected in
series is used. A temperature of 40.degree. C., a flow rate of 0.6
ml/min, and an RI (refractive index) are adopted as measurement
conditions, and a tetrahydrofuran (THF) solution containing 0.1
mass % of a measurement sample is subjected to the measurement.
Monodisperse standard polystyrenes (trade name: TSK Standard
Polystyrene F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000,
A-2500, A-1000, and A-500; manufactured by TOSOH CORPORATION) are
prepared as standard samples. A calibration curve is created with
the standard samples. A molecular weight distribution is obtained
from the retention time of the measurement sample or the number of
counts. The weight-average molecular weight Mw can be determined
from the molecular weight distribution.
The component (A) can be obtained by a known method. The component
(A) can be obtained, for example, by using an
organocyclopolysiloxane such as a dimethylcyclopolysiloxane or a
methylvinylcyclopolysiloxane and a hexaorganodisiloxane such as
hexamethyldisiloxane or 1,3-divinyl-1,1,3,3-tetramethyldisiloxane,
and subjecting the compounds to an equilibration reaction in the
presence of an alkali catalyst or an acid catalyst.
Examples of the component (B) include a methyl hydrogen
polysiloxane and an ethyl hydrogen polysiloxane. Only one kind of
those materials may be used, or two or more kinds thereof may be
used in combination. The hydrogen atom of a hydrosilyl group of the
component (B) may be bonded to a silicon atom at a terminal of its
molecular chain, or may be bonded to a silicon atom somewhere along
the molecular chain. The weight-average molecular weight of the
component (B) preferably falls within the range of 300 to 100,000.
In addition, the content of the component (B) in the
addition-curing silicone rubber composition is preferably such an
amount that a molar ratio of the hydrogen atoms bonded to the
silicon atom of the component (B) to the alkenyl groups bonded to
the silicon atom in the component (A) is 1.0 or more and 10.0 or
less. The molar ratio is more preferably 1.0 or more and 3.0 or
less.
Examples of the platinum-based catalyst as the component (C)
include a platinum fine powder, platinum black, chloroplatinic
acid, an alcohol-modified chloroplatinic acid, an olefin complex of
chloroplatinic acid, and a complex of chloroplatinic acid and an
alkenylsiloxane. Only one kind of those materials may be used, or
two or more kinds thereof may be used in combination. The content
of the component (C) in the addition-curing silicone rubber
composition is preferably such an amount that a ratio of the mass
of the catalytic metal atom of the component (C) to the mass of the
component (A) is 1 ppm by mass or more and 100 ppm by mass or
less.
By the way, the P1 and P2 in the elastic layer of the present
invention can be controlled by adjusting at least one of the
following items (i) and (ii).
(i) The Content of the Compound Represented by the Formula (1) in
the Component (A)
The compound represented by the formula (1) is inevitably produced
in a production process for a polysiloxane. In addition, the
compound represented by the formula (1) is incorporated in a
particularly large amount into the component (A), i.e., the
organopolysiloxane having, in a molecule thereof, two or more
alkenyl groups bonded to a silicon atom in the addition-curing
silicone rubber mixture as a raw material for the elastic
layer.
In addition, the compound represented by the formula (1) is
volatilized by warming the organopolysiloxane having, in a molecule
thereof, two or more alkenyl groups bonded to a silicon atom to a
temperature of 60 to 70.degree. C. under a reduced pressure of 0.01
to 0.001 MPa. Therefore, the amounts of the compounds represented
by the formula (1) in the component (A), i.e., the content of such
compound that n in the formula (1) represents an integer of 3 or
more and 12 or less, and the content of such compound that n in the
formula (1) represents an integer of 13 or more and 20 or less can
be adjusted by adjusting a time for the warming. It should be noted
that in the following description, the content of such compound
that n in the formula (1) represents an integer of 3 or more and 12
or less in the component (A) is represented by p1 ppm by mass, and
the content of such compound that n in the formula (1) represents
an integer of 13 or more and 20 or less in the component (A) is
represented by p2 ppm by mass.
In addition, the P1 and P2 in the elastic layer can be controlled
by using the organopolysiloxane having, in a molecule thereof, two
or more alkenyl groups bonded to a silicon atom in which the
amounts of the compounds according to the formula (1) have been
adjusted as a raw material for the elastic layer.
(ii) the Adjustment of a Curing Temperature and Curing Time for the
Addition-Curing Silicone Rubber Mixture
The elastic layer is obtained by: forming a layer formed of the
addition-curing silicone rubber mixture on the outer peripheral
portion of the substrate; and heating the layer to about 100 to
200.degree. C. to cure the layer. In the process as well, the
compound according to the formula (1) in the silicone rubber
mixture volatilizes. Accordingly, the P1 and the P2 can be
controlled also by appropriately adjusting a temperature for the
heating and a time for the heating.
For example, suppose that the addition-curing silicone rubber
mixture containing the component (A) having a p1 of 19,440 ppm by
mass and a p2 of 14,270 ppm by mass is filled into a cylindrical
mold having an inner diameter of 12 mm in which a mandrel having an
outer diameter of 6 mm is placed. In the case where the mixture is
heated to form the elastic layer, setting a temperature for the
heating to 115.degree. C. and a time for the heating to 5 minutes
can control a ratio (p1/P1) of the p1 to the P1 to 16 to 17% and a
ratio (p2/P2) of the p2 to the P2 to about 36 to 37%. In addition,
setting the heating temperature to 115.degree. C. and the heating
time to 3 minutes can control the ratio p1/P1 to about 30 to 31%
and the ratio p2/P2 to about 40 to 41%. Further, setting the
heating temperature to 130.degree. C. and the heating time to 5
minutes can control the ratio p1/P1 to 9 to 10% and the ratio p2/P2
to 24 to 25%.
In addition, suppose that the addition-curing silicone rubber
mixture containing the component (A) having a p1 of 30,130 ppm by
mass and a p2 of 14,050 ppm by mass is filled. In the case where
the mixture is heated to form the elastic layer, setting a
temperature for the heating to 115.degree. C. and a time for the
heating to 5 minutes can control a ratio (p1/P1) of the p1 to the
P1 to about 19 to 21% and a ratio (p2/P2) of the p2 to the P2 to
about 19 to 21%. In addition, setting the heating temperature to
130.degree. C. and the heating time to 5 minutes can control the
ratio p1/P1 to about 11 to 13% and the ratio p2/P2 to about 11 to
13%. Further, setting the heating temperature to 140.degree. C. and
the heating time to 3 minutes can control the ratio p1/P1 to about
19 to 20% and the ratio p2/P2 to 2 to 3%.
Further, suppose that the addition-curing silicone rubber mixture
containing the component (A) having a p1 of 12,240 ppm by mass and
a p2 of 18,510 ppm by mass is filled. In the case where the mixture
is heated to form the elastic layer, setting a temperature for the
heating to 115.degree. C. and a time for the heating to 5 minutes
can control a ratio (p1/P1) of the p1 to the P1 to about 28 to 29%
and a ratio (p2/P2) of the p2 to the P2 to about 43 to 44%. In
addition, setting the heating temperature to 130.degree. C. and the
heating time to 5 minutes can control the ratio p1/P1 to about 13
to 15% and the ratio p2/P2 to about 36 to 38%. Further, setting the
heating temperature to 105.degree. C. and the heating time to 10
minutes can control the ratio p1/P1 to 15 to 16% and the ratio
p2/P2 to about 51 to 52%.
The elastic layer of the developing member according to the present
invention preferably further contains an inorganic filler.
Examples of the inorganic filler include diatomaceous earth, a
quartz powder, dry silica, wet silica, titanium oxide, zinc oxide,
an aluminosilicate, calcium carbonate, and carbon black. Those
inorganic fillers have effects on, for example, the heat
resistance, heat transfer, reinforcement, and extension of the
rubber. In addition, those inorganic fillers each have a
suppressing effect on the thermal expansion of the rubber. Only one
kind of those inorganic fillers may be used, or two or more kinds
thereof may be used in combination. The inorganic filler preferably
has a specific gravity of 1.5 g/cm.sup.3 or more and 2.5 g/cm.sup.3
or less.
The elastic layer of the developing member according to the present
invention contains the inorganic filler at preferably 0.1 mass % or
more and 24 mass % or less, particularly preferably 3 mass % or
more and 22 mass % or less. Setting the content of the inorganic
filler in the elastic layer within the range can suppress a
reduction in rubber elasticity such as the thermal expansion and
compression set of the elastic layer in an additionally effective
manner. It should be noted that the content of the inorganic filler
in the elastic layer can be measured by a method to be described
later.
In addition to the filler, the elastic layer may contain any of
various additives such as a conductive agent, a plasticizer, a
vulcanizing agent, a vulcanization aid, a crosslinking aid, an
antioxidant, an anti-aging agent, and a processing aid as required,
as long as the functions imparted by the above-mentioned
composition are not impaired.
As means for dispersing and kneading those raw materials
constituting the elastic layer, there are given, for example,
methods each using a device such as a single-screw extruder, a
twin-screw extruder, a kneader, a two roll mill, a three roll mill,
a Banbury mixer, a continuous mixer, or a planetary mixer.
The elastic layer has elasticity which the developing member is
required to have. The hardness of the elastic layer can be set to,
for example, 20.degree. or more and 80.degree. or less in terms of
Asker C hardness. The thickness of the elastic layer can be set to,
for example, 1.5 mm or more and 6.0 mm or less.
A mold molding method, an extrusion molding method, an injection
molding method, an application molding method, or the like can be
given as a method of forming the elastic layer on the mandrel. More
specifically, for example, the following methods are given: a
method involving extruding the mandrel and a raw material for the
elastic layer according to the present invention to mold the
elastic layer, and when the raw material is a liquid, a method
involving injecting the raw material into a mold, which is obtained
by placing a cylindrical pipe and a die for holding the mandrel
placed at each of both terminals of the pipe, and heating the
material to cure the material. The surface of the elastic layer can
be modified by a surface modification method such as surface
polishing, a corona treatment, a flame treatment, or an excimer
treatment from the viewpoint of an improvement in adhesiveness with
the surface layer.
(Surface Layer)
As a material for the surface layer, there are given, for example:
a thermoplastic resin such as a styrene-based resin, a vinyl-based
resin, a polyether sulfone resin, a polycarbonate resin, a
polyphenylene oxide resin, a polyamide resin, a fluorine resin, a
cellulose-based resin, or an acrylic resin; and a heat- or
photo-curable resin such as an epoxy resin, a polyester resin, an
alkyd resin, a phenol resin, a melamine resin, a benzoguanamine
resin, a polyurethane resin, a urea resin, a silicone resin, or a
polyimide resin. Only one kind of those materials may be used
alone, or two or more kinds thereof may be used in combination.
When the developing member needs to have surface roughness, fine
particles for roughness control may be added to a dispersion for
the surface layer as a raw material for the surface layer. Fine
particles made of a polyurethane resin, a polyester resin, a
polyether resin, a polyamide resin, an acrylic resin, a
polycarbonate resin, or the like can be used as the fine particles
for roughness control. Only one kind of those fine particles may be
used, or two or more kinds thereof may be used in combination. The
fine particles for roughness control preferably have a
volume-average particle diameter of 3 .mu.m or more and 20 .mu.m or
less. In addition, the content of the fine particles for roughness
control in the surface layer is preferably 1 part by mass or more
and 50 parts by mass or less with respect to 100 parts by mass of
the resin solid content in the surface layer.
Carbon black may be further added to the dispersion for the surface
layer as the raw material for the surface layer. Examples of the
carbon black include carbon black having high conductivity such as
an EC300J or an EC600JD (trade name; manufactured by Lion
Corporation) and carbon black for rubber or carbon black for a
paint having moderate conductivity. Of those, carbon black for a
paint is preferred as the carbon black from the viewpoint of
simultaneous control of dispersibility and conductivity. Only one
kind of those materials may be used, or two or more kinds thereof
may be used in combination. The content of the carbon black in the
surface layer is preferably 3 mass % or more and 30 mass % or less
with respect to the resin component.
In addition to the above-mentioned additives, the surface layer may
contain a crosslinking agent, a plasticizer, a filler, an extender,
a vulcanizing agent, a vulcanization aid, a crosslinking aid, an
antioxidant, an anti-aging agent, a processing aid, a leveling
agent, and the like as long as the function of the surface layer is
not impaired.
The thickness of the surface layer is preferably 1 .mu.m or more
and 100 .mu.m or less. When the thickness of the surface layer is 1
.mu.m or more, its deterioration due to abrasion or the like can be
suppressed. In addition, when the thickness of the surface layer is
100 .mu.m or less, an increase in hardness of the surface of the
developing member can be suppressed, the deterioration of toner can
be suppressed, and fixation derived from the toner to the surface
of the developing member can be suppressed. The thickness of the
surface layer is more preferably 1 .mu.m or more and 50 .mu.m or
less in consideration of damage to the toner.
Although a method of forming the surface layer is not particularly
limited, the surface layer can be formed by, for example, as
described below. An application liquid for the surface layer is
prepared by dispersing and mixing the respective components of the
surface layer in a solvent to turn the components into a paint. The
top of the elastic layer is coated with the application liquid for
the surface layer and then the liquid is dried to be solidified or
is cured. A known dispersing apparatus utilizing beads such as a
sand mill, a paint shaker, a DYNO-MILL, or a pearl mill is
preferably used in the dispersion and mixing. Dip coating, ring
coating, spray coating, roll coating, or the like can be adopted as
a method for the coating.
(Process Cartridge and Electrophotographic Apparatus)
A process cartridge according to the present invention is
constituted so as to be constituted to be attachable to and
detachable from the main body of an electrophotographic apparatus,
and includes the developing member according to the present
invention. In addition, an electrophotographic apparatus according
to the present invention includes the developing member according
to the present invention. The process cartridge and
electrophotographic apparatus according to the present invention
are not limited to a copying machine, a facsimile, a printer, and
the like as long as the process cartridge and the
electrophotographic apparatus each include the developing member
according to the present invention. An electrophotographic
apparatus of a nonmagnetic, one-component developing system is
described below as an example of the process cartridge and the
electrophotographic apparatus each of which is mounted with the
developing member according to the present invention.
In a process cartridge illustrated in FIG. 2, a developing device
10 includes: a toner container storing a toner 8 as a nonmagnetic,
one-component toner; and a developing roller 1 that is positioned
at an opening portion extending in a longitudinal direction in the
toner container and is placed so as to be opposite to a
photosensitive member 5. In addition, the toner 8 is conveyed to a
developing region in a state of being carried on the surface of the
developing roller 1, and an electrostatic latent image on the
photosensitive member 5 is developed with the toner 8 conveyed by
the developing roller 1.
In an electrophotographic apparatus illustrated in FIG. 3, a
charging member 12 for charging the surface of the photosensitive
member 5, which is rotated by a rotating mechanism (not shown), to
a predetermined polarity and potential is placed on the periphery
of the photosensitive member 5. Further, an image exposing device
(not shown) for subjecting the charged surface of the
photosensitive member 5 to image exposure to form an electrostatic
latent image is placed. Further, the developing device 10 including
the developing roller 1 according to the present invention for
adhering toner onto the formed electrostatic latent image to
develop the image is placed on the periphery of the photosensitive
member 5. Further, a cleaning device 13 for cleaning the top of the
photosensitive member 5 after the transfer of a toner image onto
paper 22 is provided. A fixing device 15 for fixing the transferred
toner image onto the paper 22 is placed on a path along which the
paper 22 is conveyed.
Hereinafter, the present invention is described in more detail by
way of specific examples, provided that the present invention is
not limited to the examples.
<Both-Terminal-Vinyl-Sealed Polydimethylsiloxane A-5>
A both-terminal-vinyl-sealed polydimethylsiloxane (trade name:
DMS-V42; manufactured by Gelest, Inc.; weight-average molecular
weight Mw=70,000) was prepared as a both-terminal-vinyl-sealed
polydimethylsiloxane A-5.
The p1 and p2 in the both-terminal-vinyl-sealed
polydimethylsiloxane A-5 were measured by the following method.
That is, 1.0 g of the both-terminal-vinyl-sealed
polydimethylsiloxane A-5 was immersed in 10 ml of acetone for 24
hours. The supernatant of the extract was analyzed with a gas
chromatograph (product name: GC-9A (FID specification);
manufactured by Shimadzu Corporation). Such compounds that n in the
formula (1) represented 3 to 20 were identified from the resultant
MS spectrum and then their amounts were determined from the
resultant peak intensities. Table 1 shows the results. It should be
noted that the content of such a compound that n in the formula (1)
represented an integer of 3 or more and 12 or less was represented
by p1 ppm by mass, and the content of such a compound that n in the
formula (1) represented an integer of 13 or more and 20 or less was
represented by p2 ppm by mass.
<Preparation of Both-Terminal-Vinyl-Sealed Polydimethylsiloxanes
A-1 to A-4>
A low-molecular weight siloxane in the both-terminal-vinyl-sealed
polydimethylsiloxane A-5 was volatilized by maintaining a state
where the both-terminal-vinyl-sealed polydimethylsiloxane A-5 was
warmed to a temperature of 60.degree. C. under a reduced pressure
of 0.004 MPa for a predetermined time period. Thus,
both-terminal-vinyl-sealed polydimethylsiloxanes A-1 to A-4 the p1
and p2 of each of which had values shown in Table 1 were prepared.
It should be noted that the warming time was adjusted within the
range of 1 to 3 hours.
TABLE-US-00001 TABLE 1 Weight-average Low-molecular weight
Both-terminal-vinyl- molecular siloxane amount sealed polydimethyl-
weight (ppm by mass) siloxane component [Mw] p1 p2 p1 + p2 A-1
70,000 19,440 14,270 33,710 A-2 70,000 30,130 14,050 44,180 A-3
70,000 12,240 18,510 30,750 A-4 70,000 29,830 6,480 36,310 A-5
70,000 42,030 25,270 67,300
Example 1
<Preparation of Mandrel 2>
Prepared as the mandrel 2 was a product obtained by: applying a
primer (trade name: DY35-051; manufactured by Dow Corning Toray
Co., Ltd.) to a cored bar made of SUS304 having an outer diameter
of 6 mm and a length of 250 mm; and baking the primer at
170.degree. C. for 20 minutes.
<Formation of Elastic Layer 3>
The prepared mandrel 2 was placed in a cylindrical mold having an
inner diameter of 12 mm so as to be concentric with the mold. An
addition-curing silicone rubber composition was prepared as a raw
material for the elastic layer by mixing materials shown in Table
2, and then the composition was injected into the mold. After the
composition had been heated and molded at 115.degree. C. for 5
minutes, the mold was cooled to 50.degree. C. and then the elastic
layer 3 integral with the mandrel 2 was taken out of the mold.
Thus, the elastic layer 3 having a diameter of 12 mm was provided
for the outer periphery of the mandrel 2.
TABLE-US-00002 TABLE 2 Both-terminal-vinyl-sealed 100 parts by mass
polydimethylsiloxane A-1 Methyl hydrogen polysiloxane 5 parts by
mass (trade name: HMS-301; manufactured by Gelest, Inc.) Platinum
catalyst 0.05 part by mass (trade name: SIP6832.2; manufactured by
Gelest, Inc.) Carbon black 3 parts by mass (trade name: DENKA BLACK
powdery product; manufactured by DENKI KAGAKU KOGYO KABUSHIKI
KAISHA) Quartz 12.4 parts by mass (trade name: VX-S2; manufactured
by TATSUMORI LTD.)
<Formation of Surface Layer 4>
100.0 Parts by mass of a polyester polyol (trade name: Nippolan
3027; manufactured by Nippon Polyurethane Industry Co., Ltd.),
102.6 parts by mass of an MDI-based polyisocyanate (trade name:
C2521; manufactured by Nippon Polyurethane Industry Co., Ltd.), and
33.7 parts by mass of carbon black (trade name: MA230; manufactured
by Mitsubishi Chemical Corporation) as materials for the surface
layer 4 were stirred and mixed. After that, the mixed liquid was
dissolved in methyl ethyl ketone (MEK) so that the solid content
was 30 mass %, followed by mixing. After that, the contents were
uniformly dispersed with a sand mill. MEK was further added to the
mixed liquid to adjust the solid content to 25 mass %. 20 Parts by
mass of polyurethane resin particles (trade name: Art Pearl C400
(having a volume-average particle diameter of 14 .mu.m);
manufactured by Negami Chemical Industrial Co., Ltd.) were added to
the mixed liquid, and then the contents were stirred and dispersed
with a ball mill. Thus, an application liquid for the surface layer
was obtained.
The elastic layer 3 provided for the outer periphery of the mandrel
2 was subjected to dip coating with the application liquid for the
surface layer 4. Thus, the application liquid for the surface layer
4 was applied to the surface of the elastic layer 3 so that the
thickness of the application liquid was 13 .mu.m. The application
liquid was dried in an oven at 80.degree. C. for 15 minutes and
then cured in an oven at 140.degree. C. for 1 hour to form the
surface layer 4. Thus, the developing roller 1 was produced.
(Measurement of P1 and P2)
1.0 Gram of a sample was cut out of the elastic layer 3 of the
resultant developing roller 1. The sample was immersed in 10 ml of
acetone for 24 hours. After that, the extract was analyzed with a
gas chromatograph as in the analysis of the low-molecular weight
siloxane amount. At this time, the content of such a compound that
n in the formula (1) represented 3 to 12 in the sample was
represented by P1 and the content of such a compound that n in the
formula (1) represented 13 to 20 in the sample was represented by
P2. Table 4 shows the results.
(Measurement of Content of Inorganic Filler)
The thermogravimetric reduction curve of the resultant developing
roller 1 was measured with a simultaneous
thermogravimetric-differential thermal analyzer (trade name: Thermo
Plus TG8120; manufactured by Rigaku Corporation). Measurement
conditions are as described below. An amount between 15 mg and 20
mg of a sample was cut out of the elastic layer 3 of the developing
roller 1 and then set in the TG apparatus. After that, oxygen was
flowed for 15 minutes or more and then the temperature of the
sample was increased to 700.degree. C. at a rate of temperature
increase of 20.degree. C./min. The mass % (X) of the residue at the
time was calculated. In addition, nitrogen was similarly flowed for
15 minutes or more, and then the temperature was increased to
700.degree. C. at a rate of temperature increase of 20.degree.
C./min and held at the value for 10 minutes. After that, the
temperature was decreased to 300.degree. C. at a rate of
temperature decrease of 20.degree. C./min. After that, oxygen was
flowed for 15 minutes or more, and then the temperature was
increased to 800.degree. C. at a rate of temperature increase of
20.degree. C./min and held at the value for 10 minutes. After that,
a mass reduction amount (mass %) (Y) after the flow of oxygen was
calculated. X+Y was calculated as the content (mass %) of an
inorganic filler. Table 7 shows the content (mass %) of the
inorganic filler.
(Measurement of Expansion Amount)
The outer diameter dimension of the resultant developing roller 1
was measured with a device illustrated in FIG. 4. The device
includes a laser dimension-measuring machine (trade name:
"LS-7000"; manufactured by KEYENCE CORPORATION) formed of a mandrel
receiver (not shown) that rotates with reference to the developing
roller 1, an encoder (not shown) for detecting the rotation of the
developing roller 1, a reference plate 25, a laser emitting
portion, and a laser receiving portion. The outer diameter
dimension of the developing roller 1 was calculated by measuring a
gap amount 26 between the surface of the developing roller 1 and
the reference plate 25. It should be noted that the measurement of
the gap amount 26 between the surface of the developing roller 1
and the reference plate 25 was performed for a total of three
portions, i.e., a central portion in the longitudinal diction of
the elastic layer 3, and positions distant from both end portions
of the elastic layer 3 toward the central portion in the
longitudinal direction by 5.0 mm each. In addition, the measurement
was performed for 360 points at a pitch of 1.degree. with respect
to one round of the developing roller 1. The developing roller 1
was left at rest in an environment at 30.degree. C. and a relative
humidity of 55% RH for 24 hours before the measurement was
performed in the same environment. In addition, the measurement was
similarly performed in an environment at 15.degree. C. and a
relative humidity of 55%, and a difference between the measured
value, and the outer diameter dimension at 30.degree. C. and a
relative humidity of 55% RH was defined as an expansion amount
(.mu.m). Table 7 shows the result.
(Measurement of Deformation Amount and Horizontal Streak Image
Evaluation)
A process cartridge (trade name: EP-85 Toner Cartridge (black);
manufactured by Canon Inc.) of a laser beam printer having a
construction illustrated in FIG. 3 (trade name: LBP5500;
manufactured by Canon Inc.) was prepared. The toner container of
the process cartridge was mounted with a toner amount regulating
member 9 and the resultant developing roller 1, and then the
process cartridge was left at rest under an environment at
40.degree. C. and a relative humidity of 95% RH for 1 month in a
state where the developing roller 1 and the toner amount regulating
member 9 abutted on each other. It should be noted that a setting
was changed to one in which a plastic deformation was liable to
occur by adjusting an abutment pressure between the developing
roller 1 and the toner amount regulating member 9 to 0.6 N/cm.
After that, the process cartridge was left at rest under an
environment at 23.degree. C. and a relative humidity of 55% RH for
5 hours. The process cartridge was set in the laser beam printer to
output a halftone image, and then the image after the setting was
evaluated by criteria shown in Table 3 below.
In addition, the developing roller 1 was taken out of the process
cartridge subjected to the evaluation, and then its deformation
amount (.mu.m) was measured. It should be noted that the
deformation amount of the surface of the developing roller 1 was
measured with a laser displacement sensor (trade name: LT-9500V;
manufactured by KEYENCE CORPORATION). The deformation amount was
measured by: placing the laser displacement sensor in a direction
perpendicular to the surface of the developing roller 1 from which
the toner had been removed by air blowing; rotationally driving the
developing roller 1 at an arbitrary number of revolutions; and
reading a displacement in the circumferential direction of the
surface of the developing roller 1. The measurement was performed
for five points at a pitch of 43 mm in the longitudinal direction
and the average of the five measured values was defined as the
deformation amount. Table 7 shows the results of the image
evaluation and the results of the measurement of the deformation
amount.
TABLE-US-00003 TABLE 3 Evaluation rank Evaluation criterion A
Density nonuniformity is not observed. B Faint horizontal streaks
occur at random. C Thin horizontal streaks occur in sync with the
rotation period of the developing roller. D Clear horizontal
streaks occur in sync with the rotation period of the developing
roller.
Examples 2 to 33 and Comparative Examples 1 to 6
Developing rollers according to Examples 2 to 33 and developing
rollers according to Comparative Examples 1 to 6 were produced by
the same method as that of Example 1 except that the kind of the
polydimethylsiloxane component, the addition amount of quartz, the
heat molding temperature, and the heat molding time were changed as
shown in Tables 4 to 6. In addition, the respective developing
rollers were evaluated in the same manner as in Example 1. Tables 7
to 9 show the results of the evaluation.
TABLE-US-00004 TABLE 4 Polydimethylsiloxane Addition amount of P1
P1 + P2 Heat molding Heat molding Example component quartz (part(s)
by mass) (ppm by mass) (ppm by mass) temperature time 1 (A-1) 14
3,328 8,560 115.degree. C. 5 minutes 2 (A-1) 4 3,423 8,632
115.degree. C. 5 minutes 3 (A-1) 22 3,135 8,345 115.degree. C. 5
minutes 4 (A-1) 1 3,475 8,699 115.degree. C. 5 minutes 5 (A-1) 28
3,107 8,293 115.degree. C. 5 minutes 6 (A-2) 14 5,812 8,594
115.degree. C. 5 minutes 7 (A-2) 14 3,485 5,123 130.degree. C. 5
minutes 8 (A-3) 14 3,490 11,532 115.degree. C. 5 minutes 9 (A-3) 14
1,623 8,352 130.degree. C. 5 minutes 10 (A-2) 4 5,812 6,135
140.degree. C. 3 minutes 11 (A-1) 4 5,932 11,783 115.degree. C. 3
minutes 12 (A-1) 4 1,783 5,324 130.degree. C. 5 minutes 13 (A-3) 4
1,893 11,516 105.degree. C. 10 minutes 14 (A-2) 4 5,835 8,634
115.degree. C. 5 minutes 15 (A-2) 4 3,586 5,281 130.degree. C. 5
minutes 16 (A-3) 4 3,596 11,749 115.degree. C. 5 minutes 17 (A-3) 4
1,693 8,534 130.degree. C. 5 minutes 18 (A-2) 22 5,763 6,096
140.degree. C. 3 minutes 19 (A-1) 22 5,892 11,654 115.degree. C. 3
minutes 20 (A-1) 22 1,756 5,237 130.degree. C. 5 minutes
TABLE-US-00005 TABLE 5 Polydimethylsiloxane Addition amount of P1
P1 + P2 Heat molding Heat molding Example component quartz (part(s)
by mass) (ppm by mass) (ppm by mass) temperature time 21 (A-3) 22
1,832 11,328 105.degree. C. 10 minutes 22 (A-2) 22 5,810 8,590
115.degree. C. 5 minutes 23 (A-2) 22 3,470 5,130 130.degree. C. 5
minutes 24 (A-3) 22 3,490 11,683 115.degree. C. 5 minutes 25 (A-3)
22 1,673 8,398 130.degree. C. 5 minutes 26 (A-2) 1 5,897 8,764
115.degree. C. 5 minutes 27 (A-2) 1 3,621 5,356 130.degree. C. 5
minutes 28 (A-3) 1 3,763 11,834 115.degree. C. 5 minutes 29 (A-3) 1
1,735 8,673 130.degree. C. 5 minutes 30 (A-2) 28 5,793 8,432
115.degree. C. 5 minutes 31 (A-2) 28 3,356 5,102 130.degree. C. 5
minutes 32 (A-3) 28 3,387 11,632 115.degree. C. 5 minutes 33 (A-3)
28 1,632 8,293 130.degree. C. 5 minutes
TABLE-US-00006 TABLE 6 Comparative Polydimethylsiloxane Addition
amount of P1 P1 + P2 Heat molding Heat molding Example component
quartz (part(s) by mass) (ppm by mass) (ppm by mass) temperature
time 1 (A-4) 14 6,284 8,532 115.degree. C. 5 minutes 2 (A-4) 14
3,532 4,632 130.degree. C. 5 minutes 3 (A-5) 14 3,512 12,320
115.degree. C. 10 minutes 4 (A-5) 14 1,356 8,364 130.degree. C. 10
minutes 5 (A-4) 42 6,210 8,432 115.degree. C. 5 minutes 6 (A-4) 101
6,186 8,130 115.degree. C. 5 minutes
TABLE-US-00007 TABLE 7 Inorganic Expansion Deformation Horizontal
streak filler amount amount image evaluation Example (mass %)
[.mu.m] [.mu.m] rank 1 13 14 0.7 A 2 5 16 0.9 A 3 19 13 0.8 A 4 3
20 2.1 C 5 22 12 2.2 C 6 13 13 0.9 A 7 13 21 1.1 B 8 13 12 0.9 A 9
13 15 1.3 B 10 5 25 1.7 B 11 5 15 1.2 B 12 5 23 1.9 B 13 5 16 1.7 B
14 5 19 1.4 B 15 5 24 1.7 B 16 5 15 1.6 B 17 5 18 1.9 B 18 19 20
1.5 B 19 19 11 1.1 B 20 19 21 1.9 B
TABLE-US-00008 TABLE 8 Inorganic Expansion Deformation Horizontal
streak filler amount amount image evaluation Example (mass %)
[.mu.m] [.mu.m] rank 21 19 12 1.7 B 22 19 14 1.6 B 23 19 20 1.8 B
24 19 12 1.8 B 25 19 15 1.9 B 26 3 23 2.3 C 27 3 26 2.5 C 28 3 19
2.4 C 29 3 24 2.7 C 30 22 12 2.3 C 31 22 15 2.5 C 32 22 9 2.4 C 33
22 13 2.7 C
TABLE-US-00009 TABLE 9 Inorganic Expansion Deformation Horizontal
streak Comparative filler amount amount image evaluation Example
(mass %) [.mu.m] [.mu.m] rank 1 13 17 3.4 D 2 13 33 3.3 D 3 13 11
3.1 D 4 13 20 3.5 D 5 30 13 3.5 D 6 50 8 4.5 D
As is apparent from the results shown in Tables 7 to 9, a good
electrophotographic image was obtained in each of Examples 1 to 33
because the expansion amount was small and the deformation amount
was also small. This may be because of the following reason. The P1
and the P1+P2 existed in proper ranges. As a result, the expansion
of the elastic layer 3 due to heat was reduced without any
reduction of its rubber elasticity. Accordingly, its plastic
deformation was able to be reduced, and the occurrence of a
horizontal streak image resulting from the plastic deformation and
in sync with the pitch of the developing roller was able to be
suppressed.
On the other hand, in each of the developing rollers of Comparative
Examples 1 to 6, the deformation amount was large and a horizontal
streak resulting from a plastic deformation was remarkably observed
to occur in sync with the rotation period of the developing roller.
This may be because the P1 or the P1+P2 deviated from the proper
range and hence the deformation amount of the developing roller due
to its press contact with an abutting member enlarged.
The thermal expansion of the developing roller of Comparative
Example 2 was particularly large. This may be because the P1+P2, in
particular, deviated from the proper range and hence the molecular
motion of the silicone rubber composition could not be
suppressed.
The deformation amount of the developing roller of Comparative
Example 6 was particularly large. This may be because of the
following reason. The P1 deviated from the proper range and the
content of the inorganic filler was excessive. As a result, the
rubber elasticity reduced despite the suppression of the thermal
expansion. Accordingly, the deformation amount enlarged.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
This application claims the benefit of Japanese Patent Application
No. 2012-196992, filed Sep. 7, 2012, which is hereby incorporated
by reference herein in its entirety.
TABLE-US-00010 Reference Signs List 1 developing member (developing
roller) 2 mandrel substrate 3 elastic layer 4 surface layer 5
photosensitive member 6 cleaning member 7 toner supplying roller 8
toner 9 toner amount regulating member 10 developing device 11
laser light 12 charging member 13 cleaning device 14 charging
device for cleaning 15 fixing device 16 driving roller 17 transfer
roller 18 bias power source 19 tension roller 20 transfer
conveyance belt 21 driven roller 22 paper 23 sheet feeding roller
24 adsorbing roller 25 reference plate 26 gap amount
* * * * *